Background: Ludwigia hyssopifolia of family Onagraceae is traditionally used in the treatment of jaundice. There were no reports on the plant for both in vivo and in vitro hepatoprotective studies. Objective: The current study was aimed to evaluate the methanolic extract of aerial parts of L. hyssopifolia (LHME) for its in vitro and in vivo hepatoprotective activity against ethanol-induced oxidative damage in HepG2 cell lines and Wistar rats, respectively, and in vivo hepatoprotective activity against paracetamol and antihepatotoxic activity against D-galactosamine in rats. Materials and Methods: The antioxidant potential of the extract was investigated by employing different in vitro methods. The in vitro hepatoprotective activity of the extract was assessed by estimating cell supernatant for aspartate aminotransferase (AST), Alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) while the in vivo hepatoprotective activity of the extract was assessed on the basis of improvement in the altered level of various serum biochemical parameters and in the changes occurred in the histology of liver of the rats. Results: Among the three test doses of LHME, 100 μg/kg and 200 mg/kg were found to be the effective doses in in vitro and in vivo hepatoprotective methods, respectively. Conclusion: The extract, LHME, exhibited significant (P < 0.01) hepatoprotective activity in both in vitro and in vivo models, which may be attributed to its antioxidant property revealed in both in vitro and in vivo studies.